Microalgae-derived Co3O4 nanomaterials for catalytic CO oxidation

Efficient carbon monoxide oxidation is important to reduce its impacts on both human health and the environment. Following a sustainable synthesis route toward new catalysts, nanosized Co3O4 was synthesized based on extracts of microalgae: Spirulina platensis, Chlorella vulgaris, and Haematococcus pluvialis. Using the metabolites in the extract and applying different calcination temperatures (450, 650, 800 °C) led to Co3O4 catalysts with distinctly different properties. The obtained Co3O4 nanomaterials exhibited octahedral, nanosheet, and spherical morphologies with structural defects and surface segregation of phosphorous and potassium, originating from the extracts. The presence of P and K in the oxide nanostructures significantly improved their catalytic CO oxidation activity. When normalized by the specific surface area, the microalgae-derived catalysts exceeded a commercial benchmark catalyst. In situ studies revealed differences in oxygen mobility and carbonate formation during the reaction. The obtained insights may facilitate the development of new synthesis strategies for manufacturing highly active Co3O4 nanocatalysts.


Figure S4
Figure S4 Influence of calcination temperature: (A) crystallite size, (B) lattice parameter and volume, (C) surface area.

Figure S5
Figure S5BET isotherms for commercial and synthesized Co3O4 NMs.

Figure S13
Figure S13Tauc plots for commercial and synthesized Co3O4 NMs.

Table S1
Used media composition for Spirulina platensis cultivation.

Table S2
Used media composition for Chlorella vulgaris cultivation.

Table S4
Elemental analysis of the used microalgae extract.

Table S5
FTIR values of Spirulina platensis extract.

Table S6
FTIR values of Chlorella vulgaris extract.